Conceptual Design of the Beamline for the DTT Neutral Beam Injector following a Double Beam Source Design Approach

The main purpose of the Divertor Tokamak Test facility (DTT) [1], whose construction is starting in Frascati, Italy, is to study solutions to mitigate the issue of power exhaust in conditions relevant for ITER and DEMO. DTT will be equipped with a significant amount of auxiliary heating power (45 MW) to reach PSEP/R = 15 MW m-1 required to be DEMO-relevant [2]. DDT is characterized by high flexibility for the assembling and testing of divertor components and for the different magnetic configurations to address the integrated physics and technology problems. The current conceptual design of the beamline for the DTT Neutral Beam Heating system is here presented, with a particular focus on the effect on the DTT plasma and on the technical solutions adopted to maximize the RAMI indexes (Reliability, Availability, Maintainability and Inspectability) and minimize complexity and costs. Various design options were considered, and a comprehensive set of simulations was carried out using several physics and engineering codes to drive the choice of the most suitable design options and optimize them, aiming at finding a good compromise among different requirements. This paper describes the design of the main components of the DTT NBI beamline, explaining the motivations for the main design choices.